1. Field of the Invention
The invention concerns a composition that may be used to construct a substantially water impermeable barrier for containing spent oil shale.
2. Description of the Prior Art
Oil shale is becoming an increasingly important source of energy. Oil shale is a fine-grained sedimentary rock that contains organic material known as kerogen. Various retorting processes have been used or proposed to pyrolize the kerogen in the shale to yield liquid oil and gases. The liquid oil may be refined into a full slate of fuel products. Commercial scale retorting processes also yield formidable quantities of spent shale. The large amounts of spent shale from the retort process must be used or disposed of in a practical way without causing ecological damage.
While limited amounts of the spent shale may be used as an aggregate substitute in asphalt paving or in other construction applications, it appears likely that the bulk of it will be disposed by surface landfill. That is, the spent shale will be placed in natural or man-made containment basins near plant sites. Such disposal presents a potential ecological problem because the spent shale will be exposed to rain or snow which may leach various materials therefrom and contaminate indigenous water supplies.
The present invention obviates such contamination by providing a barrier member or members for such basins, in the form of an impermeable cap, bottom liner, or dam core, whose main component is a combusted shale having physical and chemical characteristics that render it especially suitable for being formed into a stable, substantially water impermeable mass. In this regard a recent U.S. Office of Technology Report "An Assessment of Oil Shale Technologies," Ch. 8, p. 334 reports that oil shales that have been retorted at high temperatures and then moistened will begin to harden within 24 hours by a curing reaction similar to that of concrete and that the hardening will continue with time. Hardening is accelerated by compaction, heat, and high pressure. Also, Processed Shale Studies: Environmental Impact Analysis, Appendix 5, Colony Development Operation, Altantic Richfield Co., 1974, proposes that processed shale might be used by local contractors to make linings for irrigation ditches and dams.
Shales have also been used to make building materials, such as wallboard. U.S. Pat. No. 1,847,366 describes a wallboard that is made from a mixture of sodium silicate, light magnesium carbonate and ground shale. U.S. Pat. No. 2,462,538 discloses building articles made by casting mixtures of burned clay or shale and a water insoluble silicate.